School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , China.
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , 1295 Ding Xi Road , Shanghai 200050 , China.
ACS Appl Mater Interfaces. 2018 Apr 18;10(15):12678-12689. doi: 10.1021/acsami.8b00989. Epub 2018 Apr 4.
Li dendrite suppression enables a highly reversible Li-metal battery. However the strategy to smooth Li surface, especially under long-term cycling and high current density, is still a big challenge. Here, we propose a facile additive strategy to reinforce Li dendrite inhibition in a range of ether and carbonate electrolytes. Dissoluble Mg(TFSI) is employed as a degradable electrolyte additive, leading to in situ plating of porous Mg network when contacting reductive Li atoms. Mg adatoms with extremely low diffusion energy barrier as lithiophilic sites enable a smooth or flaky morphology of Li surface even under a high current density of 2 mA/cm and high capacity of 6 mAh/cm. Mg-salt additive significantly extends the cycling life of Li||Cu asymmetric cells up to 240 and 200 cycles for carbonate and ether electrolytes, respectively. Under a current density as high as 5 mA/cm, the Li||Cu cell based on ether system can still survive up to 140 cycles with a small voltage hysteresis close to 60 mV. The hysteresis can be reduced to below 25 mV for lasting 200 cycles at 1 mA/cm. This additive strategy provides a facile solution to in situ construction of conductive anode-electrolyte interface with low interface resistance for alleviating uneven Li nucleation.
枝晶抑制使锂金属电池具有高可逆性。然而，在长期循环和高电流密度下，平滑锂表面的策略仍然是一个巨大的挑战。在这里，我们提出了一种简便的添加剂策略，以增强一系列醚类和碳酸盐电解液中对锂枝晶的抑制作用。可溶性 Mg(TFSI) 被用作可降解的电解质添加剂，当与还原的 Li 原子接触时，会原位形成多孔 Mg 网络。具有极低扩散能垒的 Mg 原子作为亲锂位点，即使在高电流密度 2 mA/cm 和高容量 6 mAh/cm 的条件下，也能使 Li 表面形成光滑或片状形貌。Mg 盐添加剂显著延长了碳酸盐和醚类电解液中 Li||Cu 非对称电池的循环寿命，分别达到 240 和 200 个循环。在电流密度高达 5 mA/cm 的情况下，基于醚体系的 Li||Cu 电池仍能在 140 个循环内稳定运行，电压滞后接近 60 mV。在 1 mA/cm 下，滞后可降低到 25 mV 以下，持续 200 个循环。这种添加剂策略为原位构建具有低界面电阻的导电阳极-电解质界面提供了一种简便的解决方案，从而缓解不均匀的 Li 成核。
